Veterinarians and scientists are legally and morally obligated to provide for the relief of pain and suffering in laboratory animals. Astoundingly, only anecdotal reports of analgesics and dosages recommended for use in domestic or laboratory animals appear within the literature. Many of these "guidelines" are based upon serendipitous discovery, rather than upon precisely controlled and scientifically meaningful research studies. In this project, we propose to compare multiple classes of analgesic drugs available for use in man, and reportedly efficacious for use in laboratory animals. In contrast to previous studies in rabbits, this study is unique in that we propose to characterize analgesics using controlled studies and an objective scheme of analysis. Detailed within are drugs representative of multiple classes of analgesic agents, dosage recommendations for pilot studies and planned routes of administration for drug delivery. Because pain is a complex phenomenon that involves multiple receptors, physiologic nociceptive pathways and cognitive integration, detailed methodologies are included for objective evaluation of analgesic potency and duration using a battery of thermal, mechanical somatic and visceral, and transcutaneous electrical algesiometry techniques. Each drug will also be evaluated in respect to its physiologic effects, e.g. changes in body temperature, respiration, arterial blood pressure and heart rate. Also presented is justification and a detailed description of techniques for performing this study in a humanely acceptable manner. We have chosen rabbits as the most timely species for use in this study, based upon their popularity as a surgical and immunological model, and thus, their potential exposure to a plethora of 'painful' procedures. Because approximately half a million rabbits are used yearly in the U.S. for research projects such as those mentioned above results of this study would greatly benefit laboratory animal veterinarians and investigators using this species.